1. Field of the Invention
The invention relates to a noninvasive head fixation method and apparatus for use in medical procedures to immobilize the head of a patient.
2. Description of the Prior Art
In many types of medical procedures, it is necessary to immobilize the patient's head during the medical procedure. When imaging a patient with almost any form of radiographic technique, immobilization of the patient's head is required. The imaging procedure requires a particular amount of time, and movement during that period of time may distort the image. It is also sometimes necessary to immobilize the patient's head so that the information obtained from the imaging procedure can be used at a later point in time, such as during a stereotactic procedure. In the case of a stereotactic procedure, the coordinates of a point inside the brain, which are obtained from the imaging procedure, are translated to a stereotactic apparatus attached and secured to the patient's head, so as to allow the surgeon to access a particular point either surgically or with radiation therapy. The head must not only be immobilized during the imaging procedure, but it also needs to be immobilized in the same orientation during the therapeutic procedure, such as stereotactic surgery or radiation therapy, that it had during the imaging procedure.
The patient's head must also be immobilized during cranial surgery. When precise stability and/or immobilization of the patient's head is not required during cranial surgery, noninvasive head fixation devices are often utilized to immobilize the head. If the particular surgical procedures requires delicate and precise manipulations by the surgeon, such as when a microscope is utilized, the patient's head is normally fixated through the use of an invasive head fixation device, which typically involves securing a frame to the patient's head with pins, and then clamping the frame to the imaging table or operating room table. Another form of invasive head fixation typically involves securing a plate to the patient's skull by a plurality of screws, and then securing the plate to a bracket disposed upon the imaging table or operating table.
Various types of noninvasive head fixation methods and apparatus are presently in use. Most commonly, the patient's head is secured to an imaging table with foam blocks and tape. In another system, a bite block or nasal bridge block is attached to a rod secured to an imaging table. The patient bites on the bite block while the imaging occurs, or the patient is held in place by the bridge block. In another system, the patient has an apparatus attached to his or her head for use with a nose bridge device and two ear plugs. In one system a plastic mold of the head is made, using a heat moldable material, and the plastic mold is disposed over the patient's head and is attached to the imaging table.
Of the many disadvantages associated with invasive head fixation systems, the following disadvantage is a major disadvantage. In the case of stereotactic radiosurgical procedures, a patient may require up to thirty or forty of these treatments over a six week period of time. It is not desirable to have such a patient carry a metal frame or plate upon their head during that six week period of time, in order to maintain the same orientation of the frame or plate upon the patient's head.
As to presently used noninvasive head fixation methods and apparatus, the use of a bite block can result in slightly different orientations of the patient's head with respect to the imaging or operating room table. Additionally, sanitary issues are presented by the repeated use of the bite block in repeated procedures. Additionally, bite blocks cannot be used in procedures wherein it is desired to intubate the patient, as well as such use presenting problems for patients who have difficult breathing through their nose. The use of nasal bridge blocks, because it is a generic design, makes it difficult to adequately conform the bridge block to a patient's anatomy and thus makes it extremely difficult to be precise in repositioning the patient to maintain the same orientation of the patient's head with respect to the imaging table or operating room table, during subsequent procedures.
There are additional disadvantages associated with plastic molds, in that the entire face of the patient is typically covered by the plastic material. Holes must be cut for the patient's eyes, ears, nose, and mouth, which is a time consuming process, as well as does not permit the patient to be intubated. Additionally, stereotactic invasive procedures of the patient's skull are also difficult and cumbersome to perform when this type of fixation is utilized. When the fixation system utilizing a nose bridge and two ear plugs is utilized, intubation of the patient is limited, and the associated framework prevents the use of many surgical approaches to the patient's skull.
Accordingly, prior to the development of the noninvasive head fixation method and apparatus, there has been no noninvasive head fixation method and apparatus which: is easy to use, and does not require an excessive amount of set-up time; permits the patient's head to maintain the same orientation with respect to an imaging or operating room table throughout a plurality of medical procedures; allows for intubation of the patient; and is readily usable in a wide range of surgical and nonsurgical techniques. Therefore, the art has sought a noninvasive head fixation method and apparatus which: is easy to use, and does not require an excessive amount of set-up time; permits the orientation of the patient's head with respect to an imaging or operating room table to be readily reproduced for a number of subsequent medical procedures to be done over a period of time; permits intubation of the patient; and is usable in a wide range of surgical and nonsurgical techniques.